Shigellosis, 2005

During 2005, 96 culture-confirmed cases of Shigella infection (1.9 per 100,000 population) were reported (Figure 1). This represents a 41% increase from the 68 cases reported in 2004, and a 57% decrease from the median number of cases reported annually from 1999 to 2004 (median, 222 cases, range, 68 to 904).

In 2005, S. sonnei accounted for 68 (71%) cases, S. flexneri for 27 (28%), and S. boydii for 1 (1%). Case-patients ranged in age from 3 month to 77 years (median, 14 years). Forty-seven percent of case-patients were less than 10 years of age; children less than 5 years of age accounted for 26% of cases. Sixteen (17%) case-patients were hospitalized. Sixty-seven percent of case-patients resided in the Twin Cities metropolitan area, with 33% of all case-patients residing in Hennepin County.

One waterborne outbreak of shigellosis occurred in Minnesota in 2005. Seven confirmed S. sonnei cases were identified among people who swam at a beach in Carver County on July 9. That day, the well that served the changing house, toilets, hand sinks, shower, and drinking fountain failed. Three portable toilets were provided for beach-goers. The National Weather Service reported a high temperature of 92ºF, and reports from Carver County Parks and case interviews indicated that the beach was heavily utilized that day. It is unclear how the beach water was initially contaminated; however, as Shigella is strictly a human pathogen, presumably the beach was contaminated by an ill beach-goer. The lack of changing facilities and handwashing sinks likely contributed to the outbreak.

Every tenth Shigella isolate received at MDH was tested for antimicrobial resistance. Ten isolates were tested in 2005; 40% were resistant to ampicillin, 50% were resistant to trimethoprim-sulfamethoxazole, and 20% were resistant to both ampicillin and trimethoprim-sulfamethoxazole.